304 CALIFOENIA ACADEMY OF SCIENCES. 



Distinguishable from other members of tlie genus found in this formation by 

 its elevated spire, deeply impressed suture, and small deflection. The specimen 

 described was identified by Dr. Dall. 



Rare in lower San Pedro series at Deadman Island and upper San Pedro 

 series at San Pedro. Found also in the Pleistocene at Pacific Beach, San Diego. 

 The specimen figured is somewhat decorticated, came from the upper San Pedro 

 series at San Pedro, and is now in the collection of Delos Arnold. 



Living. — Alaska to San Diego (Cooper). 



Pleistocene. — Santa Barbara to San Diego (Cooper): San Pedro; San 

 Diego (Arnold). 



Family LXXIV. FOSSARID^. 



Genus Fossarus Philippi. 



Shell perforated, sculptured; inner lip thin; aperture semilunate. 



Fossarus costatua Brocchi is a characteristic species. 



Subgenus Isapis //. d- A. Adams. 



Shell umbilicated; spire elevated; cancellated, or with revolving ribs; columella with a small 

 median tooth. 



Isapis anomala C. B. Adams is a charactei'istic species. 



337. Fossarus (Isapis) fenestrata Carpenter. 



Isapis fenesh-ala Cpr., Brit. Assn. Rept., 1863, p. 656; Ann. & Mag. Nat. Hist., 3rd Ser., Vol. XV, 

 1865, p. 28. Keep, West Coast Shells, p. 65, 1892. Williamson, Proc. U. S. Nat. 

 Mus., Vol. XV, 1892, p. 206. 



Shell small, turreted; spire elevated, subacute; whorls four, slightly convex, ornamented 

 with prominent, squarish, raised, spiral ridges, with numerous fine, oblique liruLe in the interspaces; 

 three spiral ridges on penultimate whorl, twelve to thirteen on body-whorl; suture deeply impressed, 

 distinct; aperture ovate; outer lip thin, slightly effuse; inner lip flattened, effuse; umbilical 

 chink small. 



Dimensions. — Long. 8 mm.; lat. 7 mm.; body-whorl 7 mm.; aperture, 5 mm.; defl. 

 65 degrees. 



Found in the lower San Pedro series of Deadman Island and San Pedro, and 

 in the upper San Pedro series at Crawfish George's, San Pedro, and Deadman Island. 

 Living. — Vancouver to San Diego (Carpenter). 

 Pleistocene. — San Pedro (Arnold). 



Family LXXV. RISSOID^. 



Genus Rissoa Freminville. 



.Shell minute, white or horny; conical pointed, many-whorled; smooth, ribbed or cancel- 

 lated; aperture rounded; peristome entire, continuous; outer lip slightly expanded, thickened. 



Pissoa costulata Risso is a characteristic species. 



